xref: /src/sys/ufs/ext2fs/ext2fs.h

/*	$NetBSD: ext2fs.h,v 1.6 1998/09/30 09:08:16 bouyer Exp $	*/

/*
 * Copyright (c) 1997 Manuel Bouyer.
 * Copyright (c) 1982, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)fs.h	8.10 (Berkeley) 10/27/94
 *  Modified for ext2fs by Manuel Bouyer.
 */

#include <machine/endian.h>

/*
 * Each disk drive contains some number of file systems.
 * A file system consists of a number of cylinder groups.
 * Each cylinder group has inodes and data.
 *
 * A file system is described by its super-block, which in turn
 * describes the cylinder groups.  The super-block is critical
 * data and is replicated in each cylinder group to protect against
 * catastrophic loss.  This is done at `newfs' time and the critical
 * super-block data does not change, so the copies need not be
 * referenced further unless disaster strikes.
 *
 * The first boot and super blocks are given in absolute disk addresses.
 * The byte-offset forms are preferred, as they don't imply a sector size.
 */
#define BBSIZE		1024
#define SBSIZE		1024
#define	BBOFF		((off_t)(0))
#define	SBOFF		((off_t)(BBOFF + BBSIZE))
#define	BBLOCK		((ufs_daddr_t)(0))
#define	SBLOCK		((ufs_daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))

/*
 * Addresses stored in inodes are capable of addressing blocks
 * XXX
 */

/*
 * MINBSIZE is the smallest allowable block size.
 * MINBSIZE must be big enough to hold a cylinder group block,
 * thus changes to (struct cg) must keep its size within MINBSIZE.
 * Note that super blocks are always of size SBSIZE,
 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
 */
#define LOG_MINBSIZE 10
#define MINBSIZE	(1 << LOG_MINBSIZE)

/*
 * The path name on which the file system is mounted is maintained
 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
 * the super block for this name.
 */
#define MAXMNTLEN	512

/*
 * MINFREE gives the minimum acceptable percentage of file system
 * blocks which may be free. If the freelist drops below this level
 * only the superuser may continue to allocate blocks. This may
 * be set to 0 if no reserve of free blocks is deemed necessary,
 * however throughput drops by fifty percent if the file system
 * is run at between 95% and 100% full; thus the minimum default
 * value of fs_minfree is 5%. However, to get good clustering
 * performance, 10% is a better choice. hence we use 10% as our
 * default value. With 10% free space, fragmentation is not a
 * problem, so we choose to optimize for time.
 */
#define MINFREE		5

/*
 * Super block for an ext2fs file system.
 */
struct ext2fs {
	u_int32_t  e2fs_icount;			/* Inode count */
	u_int32_t  e2fs_bcount;			/* blocks count */
	u_int32_t  e2fs_rbcount;		/* reserved blocks count */
	u_int32_t  e2fs_fbcount;		/* free blocks count */
	u_int32_t  e2fs_ficount;		/* free inodes count */
	u_int32_t  e2fs_first_dblock;	/* first data block */
	u_int32_t  e2fs_log_bsize;		/* block size = 1024*(2^e2fs_log_bsize) */
	u_int32_t  e2fs_fsize;			/* fragment size */
	u_int32_t  e2fs_bpg;			/* blocks per group */
	u_int32_t  e2fs_fpg;			/* frags per group */
	u_int32_t  e2fs_ipg;			/* inodes per group */
	u_int32_t  e2fs_mtime;			/* mount time */
	u_int32_t  e2fs_wtime;			/* write time */
	u_int16_t  e2fs_mnt_count;		/* mount count */
	u_int16_t  e2fs_max_mnt_count;	/* max mount count */
	u_int16_t  e2fs_magic;			/* magic number */
	u_int16_t  e2fs_state;			/* file system state */
	u_int16_t  e2fs_beh;			/* behavior on errors */
	u_int16_t  reserved;
	u_int32_t  e2fs_lastfsck;		/* time of last fsck */
	u_int32_t  e2fs_fsckintv;		/* max time between fscks */
	u_int32_t  e2fs_creator;		/* creator OS */
	u_int32_t  e2fs_rev;			/* revision level */
	u_int16_t  e2fs_ruid;			/* default uid for reserved blocks */
	u_int16_t  e2fs_rgid;			/* default gid for reserved blocks */
	u_int32_t  reserved2[235];
};


/* in-memory data for ext2fs */
struct m_ext2fs {
	struct ext2fs e2fs;
	u_char	e2fs_fsmnt[MAXMNTLEN];	/* name mounted on */
	int8_t	e2fs_ronly;				/* mounted read-only flag */
	int8_t	e2fs_fmod;				/* super block modified flag */
	int32_t	e2fs_bsize;				/* block size */
	int32_t e2fs_bshift;			/* ``lblkno'' calc of logical blkno */
	int32_t e2fs_bmask;				/* ``blkoff'' calc of blk offsets */
	int64_t e2fs_qbmask;			/* ~fs_bmask - for use with quad size */
	int32_t	e2fs_fsbtodb;			/* fsbtodb and dbtofsb shift constant */
	int32_t	e2fs_ncg;				/* number of cylinder groups */
	int32_t	e2fs_ngdb;				/* number of group descriptor block */
	int32_t	e2fs_ipb;				/* number of inodes per block */
	int32_t	e2fs_itpg;				/* number of inode table per group */
	struct	ext2_gd *e2fs_gd;		/* group descripors */
};



/*
 * Filesystem identification
 */
#define	E2FS_MAGIC	0xef53	/* the ext2fs magic number */
#define E2FS_REV	0		/* revision level */

/*
 * OS identification
 */
#define E2FS_OS_LINUX 0
#define E2FS_OS_HURD  1
#define E2FS_OS_MASIX 2

/*
 * Filesystem clean flags
 */
#define	E2FS_ISCLEAN	0x01
#define	E2FS_ERRORS		0x02

/* ext2 file system block group descriptor */

struct ext2_gd {
	u_int32_t ext2bgd_b_bitmap;	/* blocks bitmap block */
	u_int32_t ext2bgd_i_bitmap;	/* inodes bitmap block */
	u_int32_t ext2bgd_i_tables;	/* inodes table block  */
	u_int16_t ext2bgd_nbfree;	/* number of free blocks */
	u_int16_t ext2bgd_nifree;	/* number of free inodes */
	u_int16_t ext2bgd_ndirs;	/* number of directories */
	u_int16_t reserved;
	u_int32_t reserved2[3];

};

/* EXT2FS metadatas are stored in little-endian byte order. These macros
 * helps reading theses metadatas
 */

#if BYTE_ORDER == LITTLE_ENDIAN
#	define h2fs16(x) (x)
#	define h2fs32(x) (x)
#	define fs2h16(x) (x)
#	define fs2h32(x) (x)
#	define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE);
#	define e2fs_cgload(old, new, size) memcpy((new), (old), (size));
#	define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE);
#	define e2fs_cgsave(old, new, size) memcpy((new), (old), (size));
#else
void e2fs_sb_bswap __P((struct ext2fs *, struct ext2fs *));
void e2fs_cg_bswap __P((struct ext2_gd *, struct ext2_gd *, int));
#	define h2fs16(x) bswap16(x)
#	define h2fs32(x) bswap32(x)
#	define fs2h16(x) bswap16(x)
#	define fs2h32(x) bswap32(x)
#	define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new))
#	define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size));
#	define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new))
#	define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size));
#endif

/*
 * Turn file system block numbers into disk block addresses.
 * This maps file system blocks to device size blocks.
 */
#define fsbtodb(fs, b)	((b) << (fs)->e2fs_fsbtodb)
#define dbtofsb(fs, b)	((b) >> (fs)->e2fs_fsbtodb)

/*
 * Macros for handling inode numbers:
 *	 inode number to file system block offset.
 *	 inode number to cylinder group number.
 *	 inode number to file system block address.
 */
#define	ino_to_cg(fs, x)	(((x) - 1) / (fs)->e2fs.e2fs_ipg)
#define	ino_to_fsba(fs, x)						\
	((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \
	(((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb)
#define	ino_to_fsbo(fs, x)	(((x)-1) % (fs)->e2fs_ipb)

/*
 * Give cylinder group number for a file system block.
 * Give cylinder group block number for a file system block.
 */
#define	dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg)
#define	dtogd(fs, d) \
	(((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg)

/*
 * The following macros optimize certain frequently calculated
 * quantities by using shifts and masks in place of divisions
 * modulos and multiplications.
 */
#define blkoff(fs, loc)		/* calculates (loc % fs->e2fs_bsize) */ \
	((loc) & (fs)->e2fs_qbmask)
#define lblktosize(fs, blk)	/* calculates (blk * fs->e2fs_bsize) */ \
	((blk) << (fs)->e2fs_bshift)
#define lblkno(fs, loc)		/* calculates (loc / fs->e2fs_bsize) */ \
	((loc) >> (fs)->e2fs_bshift)
#define blkroundup(fs, size)	/* calculates roundup(size, fs->e2fs_bsize) */ \
	(((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
#define fragroundup(fs, size)	/* calculates roundup(size, fs->e2fs_bsize) */ \
	(((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
/*
 * Determine the number of available frags given a
 * percentage to hold in reserve.
 */
#define freespace(fs) \
   ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount)

/*
 * Number of indirects in a file system block.
 */
#define	NINDIR(fs)	((fs)->e2fs_bsize / sizeof(u_int32_t))